Surfactant free synthesis of high surface area Pt@PdM3 (M = Mn, Fe, Co, Ni, Cu) core/shell electrocatalysts with enhanced electrocatalytic activity and durability for PEM fuel cell applications

Abstract

A simple approach and surfactant free methodology has been employed to synthesize high surface area core/shell nano engineered electrocatalysts for fuel cell applications. Pt@PdM₃/C (M = Mn, Fe, Co, Ni, Cu) core/shell electrocatalysts were synthesized in a two stage process i.e. firstly a high surface area core was synthesised by simple borohydride reduction in ethylene glycol using a specially assembled experimental setup and then Pt was coated on the PdM₃ core surface by the polyol reduction method. The PdM₃ core was maintained in a 1 : 3 atomic ratio and the Pt shell on PdM₃ was fixed at a 1 : 3 weight ratio. XRD results confirm the covering of the PdM₃ core with the Pt shell. HR-TEM images show the distribution, shape and size of particles in high surface area carbon. The compositional studies were analyzed by SEM-EDAX and ICP-OES experiments. Electrochemical measurements were done by cyclic voltammetry, RDE and RRDE techniques. CV patterns confirmed the presence of Pt on the surface of the PdM₃ core. The Pt@PdM₃/C electrocatalyst showed an enhanced ECSA value compared to commercial Pt/C. RDE and RRDE techniques revealed that Pt@PdM₃/C core/shell nano structures follow a four electron transfer mechanism. Among all the electrocatalysts, the mass activity of Pt@PdNi₃/C is 10 fold higher than Pt/C and the specific activity of Pt@PdNi₃/C is around 20 fold higher than Pt/C. Pt@PdNi₃/C shows better enhancement in half wave potential (E_1/2) than others. The real time cell performance of the electrocatalysts revealed that Pt@PdM₃/C (M = Mn, Fe, Co, Ni, Cu) core/shell nano engineered electrocatalysts show higher performance than commercial Pt/C.